1. Field of the Invention
This invention relates generally to fibrous structures and more particularly, this invention relates to moldable composites of inorganic fibers and organic fibers and methods of production thereof.
2. Description of the Related Art
There are many applications in industry where moldable thermal and acoustical insulating materials of relatively thin cross-section are sought and needed. For example, in the automobile industry, there is a demand for moldable non-woven trunk liners, truck bed liners, roof panels and the like having sound deadening properties as well as thermal insulating properties. In the building industry there is a demand for floor, wall and ceiling materials having these same and other properties.
In the past, it has been common to use a product formed by the combination of a needled product and shoddy, i.e., wool fibers obtained by shredding pieces of unfelted woolen or worsted waste fabric, so as to obtain thermal and acoustical insulating characteristics. In practice, it is common to glue shoddy having a mastic type material on its backside, to the needled material. The combination of the shoddy and the needled material can then be attached to a product by way of the mastic on the backside of the shoddy, the combination of the shoddy and the needled product serving to provide sound deadening and heat insulating properties to the material.
U.S. Pat. No. 4,522,876 issued June 11, 1985 to Hiers discloses a textile composite fabric of non-woven, needled textile fibers suitable for use as a filtration medium or as a heat insulator, such as on the floor board of an automobile. The composite fabric comprises at least one layer of laid and needled glass fibers and at least one layer of laid and needled textile organic fibers. Needling the layers of the composite by successive stages of more aggressive needling is disclosed. The aggressive needling results in a product that is relatively highly densified, i.e., the fibers are tightly interlocked. As a result of such a densified structure, the composite fabric cannot be easily molded. In fact, the patent does not even discuss moldability with respect to the composite fabric disclosed therein. In addition, aggressive needling of highly densified fibers results in a relatively greater proportion of the needled fibers breaking as opposed to comparatively less densified fiber needling.
U.S. Pat. No. 4,568,581 issued Feb. 4, 1986 to Peoples discloses a moldable material suitable for use as fiberous surfaced panels for automobile trunk compartments and the like. The material is produced by molding a heated non-woven web formed of a blend of relatively high melting fibers, such as polyester fibers, and relatively low melting thermoplastic fibers, such as polyethylene fibers. Such fibers are relatively long in length and result in drafting, i.e., thinning out, along curves or bends when being processed in conventional molding apparatus.
Also, thin, planar needle punched materials saturated with a thermoplastic latex have been used as vehicle interior trim materials. Such materials, because they are formed in very thin sheets, are comparatively lacking in insulating properties and moldability when compared to the above-described combination of shoddy and needled material. Thicker sheets of latex saturated punched materials while providing improved insulating characteristics, are generally cost prohibitive.
The conventional materials described above typically involve several steps in their preparation. For example, materials utilizing shoddy to provide insulating properties typically require, because of the non-uniform nature of the shoddy material, a preprocessing step such as carding. Further, such materials are not easily or economically incorporated into existing production techniques and systems, such as conventional molding processes.